The subject invention is directed toward the art of snow plow couplings, and, particularly, to an improved coupling especially suited for releasably connecting snow plows or the like to vehicles such as trucks. It will be clear to those having ordinary skill in the art that the subject couplings are adapted for other than snow plows but for convenience only snow plows will be discussed.
A primary object of the invention is the provision of a releasable coupling which, when being coupled to the plow, provides a slight resistance so that the driver of the truck knows when a positive engagement has been made.
The coupling of the subject invention is designed so that the plow can readily tilt to follow road contours and the crown while simultaneously permitting raising and lowering of the plow.
Many different types of prior art coupling arrangements have been used and all suffer from a variety of defects. For example, one common problem is that during a coupling operation, the driver of the vehicle is never sure exactly when a positive engagement has been made. The usual practice is to use two men for the coupling operation, one to drive the truck forward and one to signal and perform the other needed outside operations.
A second disadvantage of many prior art couplings is that they do not permit the plow blade to have free movement for both side tilting and the usual raising and lowering. Those couplings which do satisfy the above discussed points are generally extremely complex and relatively costly.
Broadly, the invention proposes a coupling including a housing assembly adapted to be mounted on a vehicle and a loop member adapted to be connected to a plow push bar. The housing includes a first force receiving surface having a curved contour across its width. A recess extends inwardly from the curved push surface, preferably said recess has tapered lateral side walls. A hook or latch member is positioned in the recess and is adapted to pivot about an axis generally horizontal and parallel to the push surface. A forwardly facing surface of the hook member is exposed in the recess and behind said forwardly facing surface is a downwardly facing recess contoured to encompass a portion of the loop member. A guide member is positioned beneath the hook in the recess and, in combination with the forwardly facing surface defines a guide mouth such that when the housing is moved toward the loop, the hook member is cammed upwardly. Additionally, there are means for locking said hook member in a down or closed position.
The invention contemplates that the locking means will comprise a cam face extending outwardly from the hook and engaged by a pivotally mounted plate movable between a first position in which it engages the hook and a second position wherein it engages the cam face.
Preferably, the loop member has a circular cross-section and the downwardly open surface of the hook member is similarly contoured. Additionally, the loop means preferably has a V-shaped configuration generally corresponding to the lateral sides of the recess. The relationship between the loop, the side walls of the recess, and the hook, are such that the loop can both tilt and rotate a substantial amount relative to the housing while it is locked in operative position by the hook.
Accordingly, a primary object of the invention is the provision of a relatively simple plow coupling which permits tilting and lifting of the plow while connected to the truck and which also provides the driver with an indication of when a positive coupling has taken place.
Yet another object of the invention is the provision of a coupling arrangement of the general type described wherein a positive lock of the coupling is provided by a simple lever operated lock plate.